一株香蕉枯萎病拮抗菌HQB-1的分离鉴定及其发酵条件优化

【背景】香蕉枯萎病是由尖孢镰刀菌古巴专化型(Fusarium oxysporum f. sp. cubense,Foc)引起的一种真菌毁灭性土传病害,近年来施用生防菌被认为是一种有效的防治手段。【目的】从香蕉根际土壤中分离筛选具有良好防效的生防菌,并通过优化培养基及发酵条件,提高生防菌数量及抑菌效率。【方法】以福建省漳州蕉园中根际土壤为样品,以香蕉枯萎病致病菌(4号生理小种)为指示菌,通过稀释涂布、平板对峙法筛选得到一株具有较强抑菌活性的拮抗菌株HQB-1。通过形态观察、生理生化检测及16SrRNA基因序列分析,初步鉴定其种属,并采用单因素试验及正交设计优化菌株的发酵培养基及发酵条件。【结果】初步鉴定HQB-1菌株为Burkholderiastagnalis;最适培养基为:牛肉膏5.0 g/L,酵母浸粉10.0 g/L,NaCl 5.0 g/L;最佳发酵条件为:温度27°C,pH 7.0,转速200 r/min,接种量1%,培养时间36 h。【结论】使用该条件培养获得的有效活菌数及抑菌率较优化前明显提高,其中OD600由优化前的1.251提高至1.881,抑菌率由优化前的9.18%提高至34.60%。     

Sex-specific differences in body condition indices and seasonal mass loss in Tufted Puffins

ABSTRACT.   Reduced prey availability can affect the growth and survival of nestling seabirds. However, few studies have demonstrated similar effects on indices of adult body condition. We examined body condition and seasonal mass loss of breeding adult male and female Tufted Puffins ( Fratercula cirrhata ) at Chiniak Bay, Kodiak Island, Alaska, in 2004–2005. We determined sex using genetic analysis, developed a discriminant function to determine sex using morphometric measurements, and examined the body condition of adult males and females relative to the growth rates of their offspring. We found that morphological measurements were only moderately useful for sexing Tufted Puffins, with 74% of adults ( N = 176) correctly classified. We also found that the relationship between adult body mass and size differed between sexes and conclude that body condition indices must be calculated separately for each sex to avoid inter- and intrasexual bias. Body condition of male and female Tufted Puffins declined during the chick-rearing period. However, body condition of females did not differ between years, whereas male condition declined to a greater degree during 2004 when the mass of young at fledging was significantly lower. Although these results suggest that adult male Tufted Puffins sacrifice their own body condition in years of diminished nestling growth and females do not, reasons for this apparent intersexual difference in reproductive strategies remain unclear.     

Milk composition varies in relation to the presence and abundance of Balantidium coli in the mother in captive rhesus macaques (Macaca mulatta)

Primate infants require extensive maternal investment, and lactation is the most expensive aspect of this investment. However, the relationship between maternal condition and milk composition has been largely uninvestigated in primates. To better understand this relationship, I collected mid-lactation milk samples from 46 captive multiparous rhesus macaques (Macaca mulatta) at the Caribbean Primate Research Center, Sabana Seca Field Station, Puerto Rico. The maternal variables assessed were age, weight, weight for crown-rump length (CRL), and presence of parasites. Additionally the analysis included infant age, weight, and sex. Protein concentration in milk showed little interindividual variation, whereas fat had a high variance. Mothers without the lower intestinal parasite Balantidium coli had a significantly higher fat concentration in milk than mothers with B. coli, but other parasite species (Trichuris trichiura and Strongyloides fulleborni) were not associated with milk fat concentration. Females with younger infants had a higher fat concentration in their milk than mothers with older infants; however, the association between B. coli and milk fat remained significant after controlling for infant age. These results, obtained from a well fed captive population, indicate that even small differences among mothers are associated with milk composition.     

不同通气条件下硫代硫酸银对马铃薯试管苗生长和抗氧化酶活性的影响

以二倍体马铃薯试管苗为试材,研究不同通气条件下乙烯生理拮抗剂硫代硫酸银(STS)对试管苗生长和抗氧化酶活性影响的结果表明:通气条件下培养的试管苗茎高降低,叶面积和叶绿素含量增加,培养基中附加STS的效果更为明显,无论在通气还是不通气条件下,培养基中加STS的试管苗茎高降低,叶面积和叶绿素含量增加,均达极显著水平.通气和培养基中加STS的试管苗中丙二醛(MDA)含量下降。通气条件下超氧化物歧化酶(要SOD)、过氧化物酶(POD)和过氧化氢酶(CAT)活性提高;培养基中加STS的试管苗中SOD活性提高,POD和CAT活性下降。     

黑曲霉RAF106菌丝球形成的影响因素及对结晶紫的吸附作用

【背景】黑曲霉（Aspergillus niger）作为一种代表性丝状真菌已被广泛用于酶制剂、有机酸、抗生素等高价值代谢产物的工业生产、食品发酵、环境治理等行业,其代谢能力、发酵性能等与菌体形态密切相关。然而,黑曲霉对染料、重金属等的吸附能力与菌体形态的关系鲜有报道。【目的】探究黑曲霉菌丝球形成的影响因素及其对结晶紫的吸附作用。【方法】以从普洱茶分离的黑曲霉RAF106为研究对象,实时监测马铃薯葡萄糖培养液中黑曲霉菌丝球的形成过程;探究培养液的初始pH （4.0-10.0）、培养温度（25-45°C）、孢子接种量（5×10⁴-5×10⁶个/m L）、摇床转速（140-220 r/min）、碳源（葡萄糖、蔗糖、果糖、乳糖、醋酸钠）和氮源（硝酸钠、胰蛋白胨、酵母提取粉、氯化铵）对菌丝球形成的影响;以结晶紫为对象,研究不同菌体形态及菌丝球大小对黑曲霉吸附废水染料能力的影响。【结果】在黑曲霉RAF106中,孢子聚集、菌丝聚集均可形成菌丝球;菌丝球的大小与培养液初始p H、孢子接种量成反比,与摇床转速无关;当温度低于35°C时,菌丝球大小与温度成正比,...     

Isozymes inhibited by active site blocking: versatility of calcium indifferent hesperidin binding to phospholipase A2 and its significance

sPLA₂ is released under inflammatory conditions from neutrophils, basophils and T-cells. They cleave the cellular phospholipids leading to the release of arachidonic acid and there by provide intermediates for biosynthesis of inflammatory mediators. The focus of this study is on the interaction of hesperidin, a natural flavonoid with Group IB, IIA, and V and X isozymes of sPLA₂. Affinity of hesperidin towards PLA₂ isozymes was analyzed through enzymatic studies and molecular modeling. The experiments showed that hesperidin competitively inhibited PLA₂ with IC₅₀ of 5.1?µM. Molecular modeling studies revealed the association of hesperidin with the docking scores ?6.90, ?9.53, ?5.63 and ?8.29?kcal for isozymes Group IB, IIA, V and X of PLA₂ respectively. Their binding energy values were calculated as ?20.25, ?21.63, ?21.66 and ?33.43?kcal for the Group IB, IIA, V and X respectively. Structural model for Group V was made by homology modeling since no structural coordinates were available. Molecular dynamics studies were carried out to evaluate the structural stability of protein ligand complex. The analyses showed that hesperidin blocked the entry of the substrate to the active site of PLA₂ and it was indifferent to the differences of the isozymes. Hence, hesperidin might serve as lead for designing highly specific anti-inflammatory drugs directed to the PLA₂ isozyme specific to various diseases, with IC₅₀ value of therapeutic significance.     

Multiple biomarker approach in the fiddler crab to assess anthropogenic pollution in tropical coastal environments

Context: Fiddler crabs are important to the ecology of estuarine systems around the world, however, few studies have incorporated them as bioindicators. Urias estuary represents one of the most urbanized lagoons in the Gulf of California region and received discharges from different sources: shrimp farm, thermoelectric plant, fish processing plants, and untreated domestic and sewage wastes.

Objective: Assess the effects on anthropogenic contamination on female fiddler crabs reproduction, survival and genetic stability.

Methods: Exposition of wild crabs from a less impacted (reference) site to naturally contaminated sediments on under controlled laboratory conditions. Reproductive parameters, levels of DNA damage and mortality rates were measured, together with chemical analyses of sediments.

Results: The most contaminated sediments corresponded to the site where fish processing plants were located and the integrated biomarker response analysis revealed that the most adverse effects were produced by exposure to sediments from this site; these crabs showed higher mortality (67%) and poorer ovarian development than those crabs exposed to sediments from other sites.

Conclusions: Female crabs under pollution stress are able to trade-off reproduction for survival, and surviving animals were able to restore genetic stability possibly by activating DNA repair mechanisms. Multiple biomarker approach discriminates different coastal contamination scenarios.     

六妹羊肚菌工厂化制备液体菌种繁育条件的优化

为适合大规模工厂化制备羊肚菌液体菌种,以提高菌丝体生物量为目的,控制菌丝球直径,使用六妹羊肚菌Morchella sextelata,采用单因素、Plackett-Burman、响应面Box-Behnken实验摇瓶培养优化液体菌种制备条件,发酵罐扩大培养,具体参数为玉米淀粉2.5%、麸皮6%、酵母粉0.4%、葡萄糖2.5%、蛋白胨0.25%、磷酸二氢钾0.1%、硫酸镁0.05%、接种量10%、pH 5.5、转速200-500r/min、温度25℃、培养1-3d,在该条件下羊肚菌菌丝体干重可达16mg/mL,菌丝球直径降至1.5mm以下,密度达到2 967个/mL,从母种到栽培种仅需13-19d。本研究结果为羊肚菌工厂化液体菌种制备和栽培提供了理论基础。     

Age and growth of round goby Neogobius melanostomus associated with depth and habitat in the western basin of Lake Erie

Round goby Neogobius melanostomus were examined from the Bass Islands area in the western basin of Lake Erie, U.S.A., to determine age and growth correlations. A total of 188 specimens were collected and examined during summer 2011 with 90 aged using scale analysis. Fish were grouped by sex, depth of habitat and habitat type (anthropogenically modified shallows, natural shallows and open lake deep water). Fish ranged from 17 to 117 mm total length (L_T) and 0+ to 3+ years. Males dominated the population (1·94:1) and backcalculated age showed that both sexes grew exponentially, with male growth rate increasing faster than female. Males were significantly larger than females in L_T and mass (both P < 0·001). The relative mass index (W_r) was low for the sampled population (mean ± s.d . = 32·00 ± 26·87 g), implying that the health of the Bass Island area population is very poor when compared with the species throughout its range. This could be due to a lack of food resources related to population size or that the fish is not optimally utilizing the available food resources. In contradiction to these findings, regression slope coefficient (b), calculated using Fulton's condition factor (K) (mean ± s.d . =1·50 ± 0·20), was very low for each habitat, implying a healthy population throughout. This seemingly opposite effect may be due to more individuals per unit area in shallow waters, which would cause increased competition for resources. Poor condition may indicate that the Lake Erie population has reached saturation or may reflect indirect fitness costs associated with increasing anoxic or hypoxic hypolimnion conditions.